John Gill Commentary Numbers 24:8

"God bringeth him forth out of Egypt; He hath as it were the strength of the wild-ox: He shall eat up the nations his adversaries, And shall break their bones in pieces, And smite [them] through with his arrows." — Numbers 24:8 (ASV)

God brought him forth out of Egypt, he has as it were the
strength of an unicorn
Here he repeats what he had said in a former prophecy, (See Gill on Numbers 23:22): he shall eat up the nations his enemies: the seven nations of Canaan, which should be subdued by Israel, and that with as much ease as a lion devours its prey; nor would the Canaanites be able to make any more resistance to them than a creature in the paws of a lion; and the phrase denotes the utter destruction of them:

and shall break their bones ;
as the lion breaks the bones of such creatures that fall a prey to him; signifying that all their strength should be taken from them, their mighty men slain, and their fortified cities taken:

and pierce [them] through with his arrows :
slay them utterly.